SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0493da866d02850562a896dcd0fa61c785302b7d978fea01a8815c4a684ec0c' 
  AND token = 'KFM/Um4GwyO6Dhb+UQBllPWFvYGoNjeJjkNbQY89xu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables